ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Volume 34,Issue 8,2008 Table of Contents
1 Comparison and Analysis on Two Successive Torrential Rain
Events over Beijing in Summer of 2006
2008, 34(8):3-14.
DOI: 10.7519/j.issn.1000-0526.2008.08.001
Abstract:
Comparison and analysis on two successive torrential rain events occur red in Beijing on 31 July and 1 August of 2006 were conducted using high spatial temporal resolution data, such as autoweather station (AWS) network data, Do ppler radar data, wind profile data, satellite images and NCEP analysis data. It i s revealed that the two successive torrential rain events are affected by the sa me largescale trough at 500hPa from Hetao area of North China, but in their different temporal phases. Although the two torrential rain events have similar largescale environmental conditions, there are still slight differences in dia g nostic results. For instance, the long distance transfer of moisture from south to north and the confrontment of cold air and warm air over Beijing area in the second event become weaker compared to those in the first one. Investigation usi ng AWS and Weather Radar data shows that the two rainstorms are induced by mesos cale convective systems, developments of which are closely related to the evolut ions of mesoscale convergence lines of surface. However, the features, such as the size, shape, track, radar reflectivity and lifetime of mesoscale convective systems between the two torrential rain events, are quite different. The occurre nce and duration of easterly winds in planetary boundary layer (PBL) in Beijing few hours before the start of rainfall events seem essential to the formation of the torrential rainfalls, although vertical and temporal evolutions of easterly winds in PBL for the two events are different.
Comparison and analysis on two successive torrential rain events occur red in Beijing on 31 July and 1 August of 2006 were conducted using high spatial temporal resolution data, such as autoweather station (AWS) network data, Do ppler radar data, wind profile data, satellite images and NCEP analysis data. It i s revealed that the two successive torrential rain events are affected by the sa me largescale trough at 500hPa from Hetao area of North China, but in their different temporal phases. Although the two torrential rain events have similar largescale environmental conditions, there are still slight differences in dia g nostic results. For instance, the long distance transfer of moisture from south to north and the confrontment of cold air and warm air over Beijing area in the second event become weaker compared to those in the first one. Investigation usi ng AWS and Weather Radar data shows that the two rainstorms are induced by mesos cale convective systems, developments of which are closely related to the evolut ions of mesoscale convergence lines of surface. However, the features, such as the size, shape, track, radar reflectivity and lifetime of mesoscale convective systems between the two torrential rain events, are quite different. The occurre nce and duration of easterly winds in planetary boundary layer (PBL) in Beijing few hours before the start of rainfall events seem essential to the formation of the torrential rainfalls, although vertical and temporal evolutions of easterly winds in PBL for the two events are different.
2008, 34(8):15-21.
DOI: 10.7519/j.issn.1000-0526.2008.08.002
Abstract:
Based on the investigation of 18 Clear Air Turbulences (CAT) reported by the ai rcrafts in the area of Beijing Air Traffic Control Center during 2005 to 2008,4 sorts of CAT were classified according the atmosphere circulation. They were JET , trough, ridge and shear line. Combining the satellite images analysis, the fea tures of each sort of CAT and the method of CAT forecast were concluded. At last , a case of CAT was studied and the results showed that the edge of the upper je t stream, the wind shear and large temperature gradient were easier to produce CAT.
Based on the investigation of 18 Clear Air Turbulences (CAT) reported by the ai rcrafts in the area of Beijing Air Traffic Control Center during 2005 to 2008,4 sorts of CAT were classified according the atmosphere circulation. They were JET , trough, ridge and shear line. Combining the satellite images analysis, the fea tures of each sort of CAT and the method of CAT forecast were concluded. At last , a case of CAT was studied and the results showed that the edge of the upper je t stream, the wind shear and large temperature gradient were easier to produce CAT.
2008, 34(8):22-28.
DOI: 10.7519/j.issn.1000-0526.2008.08.003
Abstract:
The climatic characteristics of heavy fog in Urumqi in 1976-2006 w ere analyzed statistically. The results showed some features about heavy fog in Urumqi as follows: it mostly appeared in nighttime, the duration of most f og was within 3 hours. Over the past 31 years average fog days every year were 2 9.5d; it appeared from November in winter to March next year; the duration of heavy fog in winter was the longest. The fog days was decreasing gradually with the trend of collectivity in the past 31 years, its average decreasing rate was 1.9d/10 a. The fog days decreased obviously in 1990's, but increased rapidly in twenty first century. Fog occurred with the highest frequency when temperature, relative humidity, wind speed and air pressure were in 0～-10℃, 85%～95%, 0～3m·s -1 and 910～925hPa, respectively. The heavy fog in winter happened in the following con ditions of atmospheric stratification, such as lower, thicker and stronger inver sion layer.
The climatic characteristics of heavy fog in Urumqi in 1976-2006 w ere analyzed statistically. The results showed some features about heavy fog in Urumqi as follows: it mostly appeared in nighttime, the duration of most f og was within 3 hours. Over the past 31 years average fog days every year were 2 9.5d; it appeared from November in winter to March next year; the duration of heavy fog in winter was the longest. The fog days was decreasing gradually with the trend of collectivity in the past 31 years, its average decreasing rate was 1.9d/10 a. The fog days decreased obviously in 1990's, but increased rapidly in twenty first century. Fog occurred with the highest frequency when temperature, relative humidity, wind speed and air pressure were in 0～-10℃, 85%～95%, 0～3m·s -1 and 910～925hPa, respectively. The heavy fog in winter happened in the following con ditions of atmospheric stratification, such as lower, thicker and stronger inver sion layer.
2008, 34(8):29-34.
DOI: 10.7519/j.issn.1000-0526.2008.08.004
Abstract:
A statistical analysis of satellite rainfall estimation is performed using 3854 pairs of FY2C infrared cloudtop temperatures and rai nfalls from automatic meteorological observation station on 0607 June 2006 from 0000 to 0600 (Beijing Time). It is found that one hour accumulated rainfall amoun t can be estimated for Sichuan in real time based on the lowest infrared cloud top brightness temperature and the change of IR cloudtop temperature in one hou r. Using this method, a standard database for satellite rainfall estimation is es tablished. The 1h rainfall rates on 27 August 2007 from 1300 to 1900 and on 28 August 2007 from 0400 to 1600 (Beijing Time) are achieved in Sichuan based on the database. The RMSE of rainfall estimations at each IR temperature level is less than 2.0mm. The higher the lowest inf rared cloudtop temperature, the less the RMSE of the estimated rainfall rate. Th e method is feasible for the rainfall estimation of Sichuan.
A statistical analysis of satellite rainfall estimation is performed using 3854 pairs of FY2C infrared cloudtop temperatures and rai nfalls from automatic meteorological observation station on 0607 June 2006 from 0000 to 0600 (Beijing Time). It is found that one hour accumulated rainfall amoun t can be estimated for Sichuan in real time based on the lowest infrared cloud top brightness temperature and the change of IR cloudtop temperature in one hou r. Using this method, a standard database for satellite rainfall estimation is es tablished. The 1h rainfall rates on 27 August 2007 from 1300 to 1900 and on 28 August 2007 from 0400 to 1600 (Beijing Time) are achieved in Sichuan based on the database. The RMSE of rainfall estimations at each IR temperature level is less than 2.0mm. The higher the lowest inf rared cloudtop temperature, the less the RMSE of the estimated rainfall rate. Th e method is feasible for the rainfall estimation of Sichuan.
2008, 34(8):35-39.
DOI: 10.7519/j.issn.1000-0526.2008.08.005
Abstract:
In theory the disturbance generated by the ETKF (Ensemble Transform Ka lman filter) method has the same probability in the observation space, so it can complement the shortage caused by the ensemble generation scheme Breeding. Based on ETKF theory， a simple mesoscale ensemble system is built usin g the GRAPESMeso model and a case of rainfall occurred at 8th to 12th Nov 2005 is studied in order to verify whether such method can be applied into an i mperfect timevarying regional ensemble model with limited ensemble member. The experiment s indicate that this method can be used into the regional ensemble system，and it also can maintenance its priority, and the experimental shortcomin gs and the study focus in the future are also indicated.
In theory the disturbance generated by the ETKF (Ensemble Transform Ka lman filter) method has the same probability in the observation space, so it can complement the shortage caused by the ensemble generation scheme Breeding. Based on ETKF theory， a simple mesoscale ensemble system is built usin g the GRAPESMeso model and a case of rainfall occurred at 8th to 12th Nov 2005 is studied in order to verify whether such method can be applied into an i mperfect timevarying regional ensemble model with limited ensemble member. The experiment s indicate that this method can be used into the regional ensemble system，and it also can maintenance its priority, and the experimental shortcomin gs and the study focus in the future are also indicated.
2008, 34(8):40-44.
DOI: 10.7519/j.issn.1000-0526.2008.08.006
Abstract:
In order to forecast the severe convection events efficiently，two paroxysmal se vere convective events occurred on Jun 7, 2004 and on Jul 31, 2005 are analyzed. The results show that the two weather processes are very difficult to forecast. The synoptic system and the weather phenomenen are different in the two events. The movement speed of the former is more rapidly than the latter. The character s in infrared satellite picture, the Doppler radar echo and lightning site data are also different. The wind on the ground has close relation to the bow echo on the map of Doppler radar base reflectivity and the rapid reduce of Doppler rada r vertical integration liquidwater content. The persistent influence of the high value area of VIL are correspo nding to local heavy rain. The proportion of the cloudflashes in the two weath er processes is different. The nonconventional observation data are very impor tant to the severe convection events forecast.
In order to forecast the severe convection events efficiently，two paroxysmal se vere convective events occurred on Jun 7, 2004 and on Jul 31, 2005 are analyzed. The results show that the two weather processes are very difficult to forecast. The synoptic system and the weather phenomenen are different in the two events. The movement speed of the former is more rapidly than the latter. The character s in infrared satellite picture, the Doppler radar echo and lightning site data are also different. The wind on the ground has close relation to the bow echo on the map of Doppler radar base reflectivity and the rapid reduce of Doppler rada r vertical integration liquidwater content. The persistent influence of the high value area of VIL are correspo nding to local heavy rain. The proportion of the cloudflashes in the two weath er processes is different. The nonconventional observation data are very impor tant to the severe convection events forecast.
2008, 34(8):45-50.
DOI: 10.7519/j.issn.1000-0526.2008.08.007
Abstract:
Using the Doppler radar data in Changde, Hunan Province and other conventional m eteorological and radar data, the synoptic situation and mesoscale system feat ures of a super heavy rain in Hunan province caused by Meiyufront were analyze d. Results show that, the echoes experienced the stages of initial genesis, merg ing, helix band, merging, weakening and decay. The echocells moved from southw est to northeast all the time, but the full echoes moved from northwest to south east firstly, then moved out from north of Hunan province. The center of echo is low. The train effect is the major character of this event. Even though the inv erse wind regions in the imagery of velocity, the well organized secondary cir culation caused by discontinuous mesoscale jetcore at the middle level of trop osphere may be the main reason to form and sustain the train effect. The spectra l width is very homogeneous at all levels. This indicates that the stable jet at middle level is the major reason of the long duration of the event.
Using the Doppler radar data in Changde, Hunan Province and other conventional m eteorological and radar data, the synoptic situation and mesoscale system feat ures of a super heavy rain in Hunan province caused by Meiyufront were analyze d. Results show that, the echoes experienced the stages of initial genesis, merg ing, helix band, merging, weakening and decay. The echocells moved from southw est to northeast all the time, but the full echoes moved from northwest to south east firstly, then moved out from north of Hunan province. The center of echo is low. The train effect is the major character of this event. Even though the inv erse wind regions in the imagery of velocity, the well organized secondary cir culation caused by discontinuous mesoscale jetcore at the middle level of trop osphere may be the main reason to form and sustain the train effect. The spectra l width is very homogeneous at all levels. This indicates that the stable jet at middle level is the major reason of the long duration of the event.
2008, 34(8):51-57.
DOI: 10.7519/j.issn.1000-0526.2008.08.008
Abstract:
The spatial variability of precipitation distribution is important for land surface hydrology parameterization of GCM. By use of intensified hourly da ta over Huaihe basin during 1998-2003 summer, an analysis is made to study the s patial distribution of precipitation over this area. Results show that the preci pitation spatial distribution is heterogeneous with a close relation to the aver age precipitation intensity and coverage area. Statistical evidence suggests tha t PDF (probability density function) of coverage area and occurrence frequency p robably presented stable mode with properly interval mean rain intensity. The di screte scheme of random precipitation can be used successfully to generate the p recipitation distribution in sub grid.
The spatial variability of precipitation distribution is important for land surface hydrology parameterization of GCM. By use of intensified hourly da ta over Huaihe basin during 1998-2003 summer, an analysis is made to study the s patial distribution of precipitation over this area. Results show that the preci pitation spatial distribution is heterogeneous with a close relation to the aver age precipitation intensity and coverage area. Statistical evidence suggests tha t PDF (probability density function) of coverage area and occurrence frequency p robably presented stable mode with properly interval mean rain intensity. The di screte scheme of random precipitation can be used successfully to generate the p recipitation distribution in sub grid.
2008, 34(8):58-62.
DOI: 10.7519/j.issn.1000-0526.2008.08.009
Abstract:
Based on daily precipitation data of five weather stations of Dongying City from 1971 to 2004, the characteristic of rainstorm change and the produce reasons in this region are studied by using Petitt method and composite analysis. The resu lts show that the interdecadal variation of Dongying rainstorm has pr esented 3 characteristic time intervals since the 1970s. The abrupt change of ra instorm happens in 1974/1975. The rainstorm has a trend of escalation before abr uption, and it quickly reduced after abruption. 1990 was the secondlevel chang e point, afterward the rainstorm frequency obviously increased. Increase in Dong ying rainstorm after 1990's is attributable to the advantageous upper air circul ation background, frequent interaction between the north cold air and south warm and humid air streams. As a result of the Dongying special geographical positio n, the terrain and landform influence cause the Dongying precipitation's climate characteristics being inconsistent with that of Shandong Province. The former c hange is counter parabola shape, but in the whole province it appears to be consistently decreas ing tendency.
Based on daily precipitation data of five weather stations of Dongying City from 1971 to 2004, the characteristic of rainstorm change and the produce reasons in this region are studied by using Petitt method and composite analysis. The resu lts show that the interdecadal variation of Dongying rainstorm has pr esented 3 characteristic time intervals since the 1970s. The abrupt change of ra instorm happens in 1974/1975. The rainstorm has a trend of escalation before abr uption, and it quickly reduced after abruption. 1990 was the secondlevel chang e point, afterward the rainstorm frequency obviously increased. Increase in Dong ying rainstorm after 1990's is attributable to the advantageous upper air circul ation background, frequent interaction between the north cold air and south warm and humid air streams. As a result of the Dongying special geographical positio n, the terrain and landform influence cause the Dongying precipitation's climate characteristics being inconsistent with that of Shandong Province. The former c hange is counter parabola shape, but in the whole province it appears to be consistently decreas ing tendency.
2008, 34(8):63-69.
DOI: 10.7519/j.issn.1000-0526.2008.08.010
Abstract:
By using the NCEP data of the first 10 days in July from 1998 to 2007, three hea vy flooding cases in 2003, 2005 and 2007 are analyzed and compared. It is foun d that there is an obvious difference in the atmospheric circulation background , the high/low level jets and the water vapor transportation between the floodin g years and average of ten years. The abnormal feature of the East Asian summer monsoon is the main reason of the floods. During the first 10 days in July of t he three flooding years, the west pacific subtropical high is stronger and its west ridge point is more western than the tenyear average. There is obviously north wind from the south of northChina to the Huanghe and Huaihe basin. The low jets of 850hP a surpassed 6m/s larger than the tenyear mean. The connection of the north and the south strong air current exactly lied in Huaihe River basin. At 200hPa, Hua ihe River basin was under the south of the jets entrance or under the anticyclon e. Through the analysis of abnormal water vapor transportation on the whole laye r, it is found that the South China Sea was the main water vapor source area.
By using the NCEP data of the first 10 days in July from 1998 to 2007, three hea vy flooding cases in 2003, 2005 and 2007 are analyzed and compared. It is foun d that there is an obvious difference in the atmospheric circulation background , the high/low level jets and the water vapor transportation between the floodin g years and average of ten years. The abnormal feature of the East Asian summer monsoon is the main reason of the floods. During the first 10 days in July of t he three flooding years, the west pacific subtropical high is stronger and its west ridge point is more western than the tenyear average. There is obviously north wind from the south of northChina to the Huanghe and Huaihe basin. The low jets of 850hP a surpassed 6m/s larger than the tenyear mean. The connection of the north and the south strong air current exactly lied in Huaihe River basin. At 200hPa, Hua ihe River basin was under the south of the jets entrance or under the anticyclon e. Through the analysis of abnormal water vapor transportation on the whole laye r, it is found that the South China Sea was the main water vapor source area.
2008, 34(8):70-76.
DOI: 10.7519/j.issn.1000-0526.2008.08.011
Abstract:
There are several similar characteristics in Meiyu period of 2003 and 2006. For example, the date of beginning and ending of Meiyu was consistent in above two years, the subtropical high ridge of Meiyu period of the two years also oscillated between 15°N and 27°N, and the heavy rainstorm during Meiyu period of the two year concentrated in Huaihe valley, Hongze lake and Lixiahe area of Jiangsu. But the total precipitation of Meiyu period in 2003 was more than that in 2006. The synoptic situation and conditions of thermodynamics and dynamics wh ich accompanied with heavy rainstorm during Meiyu period of 2003 and 2006 in Jia nghuai valley of Jiangsu are analyzed in details by using the T213 analysis data and composite average method. The results show that Meiyu front of 2003 is stro nger. In addition, the stable moisture transportation, overlappingcenter of converge nce and vorticity and vigorous ascending stream in 2003 were also favorable co nditions for the Meiyu. The number of heavy rainstorm day caused by strong convect ive system in 2006 was more than in 2003. The results also indicate that the rainfall amount in the period of Meiyu is proportional to the increment in the phys ical quantity.
There are several similar characteristics in Meiyu period of 2003 and 2006. For example, the date of beginning and ending of Meiyu was consistent in above two years, the subtropical high ridge of Meiyu period of the two years also oscillated between 15°N and 27°N, and the heavy rainstorm during Meiyu period of the two year concentrated in Huaihe valley, Hongze lake and Lixiahe area of Jiangsu. But the total precipitation of Meiyu period in 2003 was more than that in 2006. The synoptic situation and conditions of thermodynamics and dynamics wh ich accompanied with heavy rainstorm during Meiyu period of 2003 and 2006 in Jia nghuai valley of Jiangsu are analyzed in details by using the T213 analysis data and composite average method. The results show that Meiyu front of 2003 is stro nger. In addition, the stable moisture transportation, overlappingcenter of converge nce and vorticity and vigorous ascending stream in 2003 were also favorable co nditions for the Meiyu. The number of heavy rainstorm day caused by strong convect ive system in 2006 was more than in 2003. The results also indicate that the rainfall amount in the period of Meiyu is proportional to the increment in the phys ical quantity.
12 The Application of Quality Control Procedures for
Realtime Data from Automatic Weather Stations
2008, 34(8):77-81.
DOI: 10.7519/j.issn.1000-0526.2008.08.012
Abstract:
Quality Control for data from automatic weather stations is very important with the development of society and technology. Beijing Meteorological Bureau has cre ated realtime Quality Control system for automatic weather stations (AWS) whic h has applied on the 2007 Olympic Games Drilling. The scheme of Quality Control for data mainly includes methods, such as plausible value check, time c onsistency check, internal consistency check, history value check, spatial check , etc. The application of the data quality control system to 2007 Olympic Games Drilling in Beijing area shows that Beijing AWS data is reliable, but there are some problems on missing and timely data. This system will become a good example of real-time processing for AWS Quality Control in Beijing 2008 Olympic Games weather servic es.
Quality Control for data from automatic weather stations is very important with the development of society and technology. Beijing Meteorological Bureau has cre ated realtime Quality Control system for automatic weather stations (AWS) whic h has applied on the 2007 Olympic Games Drilling. The scheme of Quality Control for data mainly includes methods, such as plausible value check, time c onsistency check, internal consistency check, history value check, spatial check , etc. The application of the data quality control system to 2007 Olympic Games Drilling in Beijing area shows that Beijing AWS data is reliable, but there are some problems on missing and timely data. This system will become a good example of real-time processing for AWS Quality Control in Beijing 2008 Olympic Games weather servic es.
2008, 34(8):82-86.
DOI: 10.7519/j.issn.1000-0526.2008.08.013
Abstract:
In order to deeply develop the meteorological prediction and climate impact asse ssment of heatstroke by heat wave, the daily heat stroke cases and meteorologi cal factors from 2003 to 2005 in Wuhan are used to choose the key factors by cor relative method. Three regressive models are set up with progressive regr ession on the basis of calculating the single-correlation coefficient of daily h eat stroke numbers and 33 meteorological factors, and the more reasonable grade standards than original model of 1990's are also built up, and a method to calcu l ate days with heatstroke event is designed. The results show that the factors co ncerned temperature are the most important, and the accumulated temperature ≥35 ℃ is selected at first. By experimental test, the results show that the forecas ting value and the real value are relatively identical.
In order to deeply develop the meteorological prediction and climate impact asse ssment of heatstroke by heat wave, the daily heat stroke cases and meteorologi cal factors from 2003 to 2005 in Wuhan are used to choose the key factors by cor relative method. Three regressive models are set up with progressive regr ession on the basis of calculating the single-correlation coefficient of daily h eat stroke numbers and 33 meteorological factors, and the more reasonable grade standards than original model of 1990's are also built up, and a method to calcu l ate days with heatstroke event is designed. The results show that the factors co ncerned temperature are the most important, and the accumulated temperature ≥35 ℃ is selected at first. By experimental test, the results show that the forecas ting value and the real value are relatively identical.
2008, 34(8):87-94.
DOI: 10.7519/j.issn.1000-0526.2008.08.014
Abstract:
By using the NCEP 1°×1° grid point material and the convention observed data, a heavy fog process in the mountainous region occurred in KunmingDaluo high w ay in Yunnan in the end of December 2005 was diagnostically analyzed. The result shows that this fog ever happened at the southwest side of strong cold high pre ssure of ground in the weather background when the continuous and incessant rain stopped and turned to clear day. The ground radiation cooling effect trigge red and strengthened the mountainous region fog, and the topography leeward slop e obviously strengthened the effect on the fog of mountain region. When fog form ed, 850～800hPa level has an obvious inversion layer or the neutrosphere. The st ronger the inversion layer, the heavier the mountainous region fog. The breeze in the surface layer is advantageous in forming the fog.
By using the NCEP 1°×1° grid point material and the convention observed data, a heavy fog process in the mountainous region occurred in KunmingDaluo high w ay in Yunnan in the end of December 2005 was diagnostically analyzed. The result shows that this fog ever happened at the southwest side of strong cold high pre ssure of ground in the weather background when the continuous and incessant rain stopped and turned to clear day. The ground radiation cooling effect trigge red and strengthened the mountainous region fog, and the topography leeward slop e obviously strengthened the effect on the fog of mountain region. When fog form ed, 850～800hPa level has an obvious inversion layer or the neutrosphere. The st ronger the inversion layer, the heavier the mountainous region fog. The breeze in the surface layer is advantageous in forming the fog.
Hu Yanping
,
Tian Xiuxia
,
Zhao Guihua
,
Shan Tieliang
,
Cheng Jinxia
,
Wang Ying
,
Dong Yulun
,
Hui Fumei
2008, 34(8):95-103.
DOI: 10.7519/j.issn.1000-0526.2008.08.015
Abstract:
Based on the conventional and automatic observation data, NCEP(1°×1°) reanalysis data, the causes of two heavy rainfall events occurred on 5 and 14 J uly, 2007 in Shali river area are diagnosed and analyzed. The diagnostic results show that the dynamic conditions of two heavy rainfall events are different und er different influencing systems. The results show that the movement direction a nd intensity transformation of the positive center of the vertical helicity at 7 00hPa matches the heavy rainfall regions quite well in two heavy rainfall events . The heavy rainfall center lies on the front of the movement of the vertical he licity center. The vertical helicity value is positive at lower level while negative at upper level on July 5, whose dynamic c ondition is more beneficial for the occurrence of the heavy rainfall. The moist potential vorticity analysis indicates that the atmospheric instability at lower level of JUL-5 heavy rainfall event is not only convectively unstable but also symmetrically instable, which is favorable for the development of both vertical convection and slantwise convection. For the JUL-14 event, the lower level atmos phere is convectively stable and the boundary layer is convectively unstable. At the same time, the middle-level atmosphere is convectively unstable and has obv iously symmetric instability, so the slantwise vorticity gets a bigger growth, w hich leads to the strong ascending movement and the moist air upward transport a nd makes the precipitation intensity increase.
Based on the conventional and automatic observation data, NCEP(1°×1°) reanalysis data, the causes of two heavy rainfall events occurred on 5 and 14 J uly, 2007 in Shali river area are diagnosed and analyzed. The diagnostic results show that the dynamic conditions of two heavy rainfall events are different und er different influencing systems. The results show that the movement direction a nd intensity transformation of the positive center of the vertical helicity at 7 00hPa matches the heavy rainfall regions quite well in two heavy rainfall events . The heavy rainfall center lies on the front of the movement of the vertical he licity center. The vertical helicity value is positive at lower level while negative at upper level on July 5, whose dynamic c ondition is more beneficial for the occurrence of the heavy rainfall. The moist potential vorticity analysis indicates that the atmospheric instability at lower level of JUL-5 heavy rainfall event is not only convectively unstable but also symmetrically instable, which is favorable for the development of both vertical convection and slantwise convection. For the JUL-14 event, the lower level atmos phere is convectively stable and the boundary layer is convectively unstable. At the same time, the middle-level atmosphere is convectively unstable and has obv iously symmetric instability, so the slantwise vorticity gets a bigger growth, w hich leads to the strong ascending movement and the moist air upward transport a nd makes the precipitation intensity increase.
2008, 34(8):104-111.
DOI: 10.7519/j.issn.1000-0526.2008.08.016
Abstract:
The CloudSat and CALIPSO satellites were launched into space from Vandenberg Air Force Base in California at approximately 6:02 a.m. EDT on April 28, 2006, begi nning a mission to study clouds from orbit. In this paper, close attentions are paid to a new type cloud detecting satelliteCloudSat. The preceding sections g ive a general overview of the detecting instruments embarked on CloudSat and the “ATrain" constellation. The main products of CloudSat and the ways to get th em are especially described, and then two samples of cloud detection by CloudSat for different kinds weather of synoptic situations are displayed. At last, the applications of CloudSat productis to some aspects of weather or climate in futu re are discussed.
The CloudSat and CALIPSO satellites were launched into space from Vandenberg Air Force Base in California at approximately 6:02 a.m. EDT on April 28, 2006, begi nning a mission to study clouds from orbit. In this paper, close attentions are paid to a new type cloud detecting satelliteCloudSat. The preceding sections g ive a general overview of the detecting instruments embarked on CloudSat and the “ATrain" constellation. The main products of CloudSat and the ways to get th em are especially described, and then two samples of cloud detection by CloudSat for different kinds weather of synoptic situations are displayed. At last, the applications of CloudSat productis to some aspects of weather or climate in futu re are discussed.
2008, 34(8):112-118.
DOI: 10.7519/j.issn.1000-0526.2008.08.017
Abstract:
From March to May every year, frequent cold fronts are usually seen in China. Be cause of active cold fronts during these 3 months, weather in china is character ized by sharp temperatures fluctuations and frequent dusty weather conditions. I n order to examine the forecasting effect of numerical model and accumulate for ecasting experiences, the 96hour forecasting product of T213 model were examin ed and analyzed and also compared its forecasting result with ECMWF model and Ja pan model. The result is: ECMWF model is more effective in midirange forecast. As for adjusting macroscale circulation and forecasting temperatures at 850hP a the ECMWF model has stronger predictive ability than the other 2 models. In ad dition, a dusty weather process occurred on 26-28 May 2008 was chosen, as a case study. Through analyzing this case, we found that Japan models were more effect ive than the other 2 models in midrange forecast of the strong surface winds, which caused this dusty weather process.
From March to May every year, frequent cold fronts are usually seen in China. Be cause of active cold fronts during these 3 months, weather in china is character ized by sharp temperatures fluctuations and frequent dusty weather conditions. I n order to examine the forecasting effect of numerical model and accumulate for ecasting experiences, the 96hour forecasting product of T213 model were examin ed and analyzed and also compared its forecasting result with ECMWF model and Ja pan model. The result is: ECMWF model is more effective in midirange forecast. As for adjusting macroscale circulation and forecasting temperatures at 850hP a the ECMWF model has stronger predictive ability than the other 2 models. In ad dition, a dusty weather process occurred on 26-28 May 2008 was chosen, as a case study. Through analyzing this case, we found that Japan models were more effect ive than the other 2 models in midrange forecast of the strong surface winds, which caused this dusty weather process.
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